Food products such as hams and certain types of sausages have commonly been placed between screens and the screens fastened together by attaching springs under tension about the periphery of the screens, the tension of the individual screens being utilized to urge the screens toward each other. This practice is tedious and requires a great amount of time and labor; also there is a tendency to press the food articles nearer the periphery of the screens to a greater degree than those in the center portion of the screens.
In the Matthews U.S. Pat. No. 3,618,511 a cage is provided having spaced shelves with presser screens above the shelves. The presser screens are moved upwardly of the shelves when the springs at the bottom of the cage are compressed to open the shelves for loading. To do this the cage is moved under an air cylinder. When the cylinder is relieved and the springs expand, the presser screens are urged against the articles on each of the shelves.
A disadvantage of the Matthews cage is that each time the cage is loaded or unloaded, it must be brought under a power source such as the air cylinder above mentioned which is an inconvenience and which limits its usefulness. Another disadvantage is that it does not utilize the weight of the food articles on the upper shelves for bringing pressure on the articles on lower shelves. Still another disadvantage is that the articles on the different shelves will receive the same pressure only if they are the same in height.
Objects of this invention are to provide a cage for compressing food articles which is effective for bringing the food articles on different trays under substantially uniform pressure. Another object is to provide such a cage which can be operated easily and without any substantial effort to open the cage for loading and for closing the cage when it is loaded. Another object is to utilize the weight of the articles on the upper trays to provide pressure for compressing the articles on the lower trays. Another object is to provide improved "sandwich" type trays having double screens with moving mechanisms between the screens.
Since in utilizing the weight of the articles on upper trays for compressing articles on lower trays, it is normal that the weight of the articles on the highest tray bears against the top tray, the weight of the articles on the two top trays bears against the second highest tray, and the weight of the articles on the top three trays bears against the third highest tray, etc., so that the pressure on the articles due to the weight of the food articles increases toward the bottom of the cage. It is a special object of this invention to provide auxiliary pressure on each of a series of trays which decreases toward the bottom of the series so that the combined pressure due to the weight of the articles and the auxiliary pressure so provided will be more nearly uniform.